1. Field of the Invention
This invention relates to a device and method for determining the time which it takes for a test subject to recognize and react to a visual signal.
2. Description of the Related Art
The inventor has been unable to locate a similar device.
A number of patents determine the speed with which a signal travels along a nerve or through skin and then along a nerve. These include U.S. Pat. Nos. 4,064,870; 4,807,643; 5,215,100; 5,313,956; and 5,388,587.
U.S. Pat. No. 4,570,640 covers a device that stimulates the skin of a test subject and then monitors the output side of the subject's central nervous system in order to determine the level and depth of spinal and epidural nerve blocks affecting the sympathetic and motor nervous system.
U.S. Pat. No. 5,263,490 discloses and claims a device that applies an electrical stimulus to a person's ulnar nerve and then measures the relaxation rate of the abductor pollicis muscle by determining the force exerted by the patient's thumb.
U.S. Pat. No. 5,381,805 deals with a device that administers "cutaneous stimulation" to a patient.
And U.S. Pat. No. 5,551,446 applies a stimulus (only a physical force is disclosed, although it is stated--but not explained--that such stimulus could be noise, light, or electrical shock) to a patient and measures the beginning of the patient's physical response to such stimulus.
Only this latter patent is intended to measure a reflex; and it simply measures an automatic reaction to a stimulus, not a response by a subject that requires both perception of a stimulus and a consciously directed response to that stimulus.